The proposed project is designed to investigate the relationship existing between the fluid contained in the follicles of mammalian ovaries, and the maternal germ cell (oocyte) during the stages of developmental change occurring prior to ovulation and conception. Preliminary experiments have led to the observation of specific differences in the protein patterns of follicular fluids at various stages of follicular development. Since mammalian immature oocytes undergo abnormal development (maturation) in the absence of the follicular environment (i.e., in vitro), it is very probable that specific constituents of the follicular fluid are required for the normal production of mature oocytes. In the proposed project, fluid and specific components of fluids from mammalian ovarian follicles at various stages of development will be used to supplement culture media for the maturation of oocytes in vitro. In addition, the follicular fluids will be fractionated biochemically and the molecular components, particularly the proteins, will be isolated, characterized and tested for biologic activity as related to oocyte maturation. Experiments are proposed for inducing inhibition of specific components of follicular fluid which prove to be required for oocyte maturation. It is proposed that these experiments will offer a unique and highly specific approach to contraception at the level of the unfertilized maternal gamete.